The present invention relates to a tool coupling comprising a holder, an adapter for at least one cutting insert for chip removing machining and a separate element in order to detachably connect the holder and the adapter with each other, said holder being provided with a first serration having mutually parallel grooves, and the adapter being provided with a second serration having mutually parallel grooves. The invention also relates to the holder and the adapter per se.
From WO 93/10929 (corresponding to Muendlein et al. U.S. Pat. No. 5,555,784), a turning tool is previously known, said turning tool having a cylindrical shaft and a head having a contact surface that rests against a support surface of the shaft. The contact surface and the support surface are arranged at an acute angle relative to the longitudinal center axis of the tool and each of said surfaces is provided with serrations having mutually parallel grooves, said serrations engaging each other when the contact surface and the support surface are resting against each other. In order to connect the shaft and the head with each other holes are provided in said elements, said holes extending essentially perpendicular to said surfaces and are located directly opposite to each other when the contact surface and the support surface are resting against each other in correct position. A threaded screw is received in said holes in order to urge the surfaces against each other and provide a reliable connection between the shaft and the head.
The holes in the shaft and the head are designed in such a way that they have a larger cross dimension in a direction perpendicular to the serrations than in the longitudinal direction of the serrations. By this arrangement it is achieved that the serrations guide the mutual orientation of the shaft and the head in a direction perpendicular to the longitudinal direction of the grooves while the fit of the hole relative to the screw guides the mutual orientation of the shaft and the head in a direction parallel to the longitudinal direction of the grooves.
Since the contact surface and the support surface form an angle with the longitudinal center axis of the tool also the threaded screw that connects the shaft with the head forms an angle with said longitudinal center axis. This arrangement causes problems as regards the provision of cooling passages that have to be located eccentrically in the shaft. Especially in connection with rotating tools it is not beneficial to locate the cooling passages eccentrically. Said eccentric location of the cooling passages also brings about that the shaft may not be used both for right-hand type tools and left-hand type tools.
The object of the present invention is to set aside the disadvantages of known tool couplings and create a tool coupling that is usable for different types of chip removing machining, e.g. milling, turning and drilling.
A primary object of the invention is that the tool coupling should be usable in connection with tools that rotate at an extremely high speed, i.e. the tool coupling should not generate vibrations or the like due to unbalance of said tool coupling.
Still an object of the invention is that the tool coupling should make it possible for the holder and the adapter to be connected with each other by means of simple connecting means, preferably of standard type.
A further object of the invention is that the tool coupling generally should be usable both for tools of right-hand type and left-hand type.
The objects of the invention are realized by means of a tool coupling that comprises a holder and an adapter detachably connected to the holder and adapted to carry a cutting insert. The holder and the adapter define a longitudinal center axis. The holder includes first serrations lying in a plane oriented transversely to the center axis. The adapter includes second serrations lying in a plane oriented transversely to the center axis. The first and second serrations are in meshing engagement with one another. The holder and the adapter include first and second cooling passages, respectively, for conducting cooling medium. A fastening screw extends in both the adapter and the holder and is arranged coaxially with the center axis. The screw is threadedly connected with the holder and includes a third cooling passsage therein for conducting cooling medium from the first cooling passage to the second cooling passage.
Preferably, the holder includes an internally threaded first opening threadedly connected to an externally threaded second end of the screw. The adapter includes a second opening in which a second end of the screw is disposed. The first and second openings have an elongated cross sectional shape defined by long and short dimensions, respectively. The long dimension extends in a direction perpendicular to the serrations, and the short dimension extends in a direction parallel to the serrations.